1. Technical Field
The present invention is related to a fixed focus imaging lens for forming optical images of subjects onto an imaging element such as a CCD (Charge Coupled Device) and a CMOS (Complementary Metal Oxide Semiconductor). The present invention is also related to an imaging apparatus provided with the imaging lens that performs photography such as a digital still camera, a cellular telephone with a built in camera, a PDA (Personal Digital Assistant), a smart phone, a tablet type terminal, and a portable gaming device.
2. Background Art
Accompanying the recent spread of personal computers in households, digital still cameras capable of inputting image data such as photographed scenes and portraits into personal computers are rapidly becoming available. In addition, many cellular telephones, smart phones, and tablet type terminals are being equipped with camera modules for inputting images. Imaging elements such as CCD's and CMOS's are employed in these devices having photography functions. Recently, miniaturization of these imaging elements is advancing, and there is demand for miniaturization of the imaging entirety of the photography devices as well as imaging lenses to be mounted thereon. At the same time, the number of pixels in imaging elements is increasing, and there is demand for high resolution and high performance of imaging lenses. Performance corresponding to 5 megapixels or greater and more preferably 8 megapixels or greater, is desired.
In response to such demands, imaging lenses having a five lens configuration, which is a comparatively large number of lenses, have been proposed, in order to shorten the total length and to increase resolution, for example. For example, U.S. Patent Application Publication No. 20110181963, U.S. Pat. No. 7,274,515, Korean Patent Publication No. 10-2009-0055115, U.S. Patent Application Publication No. 20120092778, and U.S. Patent Application Publication No. 20110181963 propose imaging lenses with five lens configurations, constituted by: a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a negative refractive power, a fourth lens having a negative refractive power, and a fifth lens, provided in this order from the object side (refer to U.S. Patent Application Publication No. 20110181963, U.S. Pat. No. 7,274,515, Korean Patent Publication No. 10-2009-0055115, U.S. Patent Application Publication No. 20120092778, and U.S. Patent Application Publication No. 20110181963).